Introduction to Various Types of Water Pumps

       Other pumps refer to special pumps other than blade pumps and volumetric pumps. The main types of other pumps include: screw pumps, jet pumps (also known as water injectors), gear pumps, turbine pumps, and air lift pumps (also known as air lifting machines). Among these pumps, except for screw pumps which use the principle of screw propulsion to increase the energy of the liquid, other pumps use the kinetic energy of high-speed liquid or gas flow (i.e., high-speed jets) to transport liquids.
       Although the application of these pumps is not as widespread as that of screw pumps, in water supply and drainage projects, using these special pumps to transport liquids under specific conditions often yields good results. For example, in urban leak treatment, when secondary sedimentation sludge flows to the aeration tank, screw pumps or air lift systems are often used for lifting; jet pumps are also commonly used in water treatment for dosing applications, typically for adding coagulants or disinfectants.
       The usage range of the various types of pumps mentioned above is quite similar. The diagram shows several commonly used types of pumps. From the diagram, it can be seen that the usage range of screw pumps focuses on high lift and low flow; diaphragm pumps and mixed flow pumps focus on low lift and high flow; centrifugal pumps have a usage range that lies between the two, with the widest working range and the most variety of products, series, and specifications.
       For urban water supply projects, the lift of water pumping stations is between 20 to 100 m, and the flow rate generally ranges from 50 to 1000 m³/h. To meet such working ranges, it is evident from the general performance diagram that using centrifugal pump installations is very suitable; even in some large water plants, multiple centrifugal pumps can be used in parallel in the pumping station to meet water supply requirements.
From the perspective of drainage projects, urban sewage pumping stations and rainwater pumping stations are characterized by large flow and low lift. The lift is generally between 2 to 12 m, and the flow can exceed 1000 m³/h. Within this working range, axial flow pumps are generally more suitable.
      In summary, in the water supply and drainage projects of towns and industrial enterprises, axial flow pumps are commonly used.
      Currently, the overall trend in pump development can be summarized as follows:
       1. Large-scale and high-capacity
      If the emergence of a 50,000 kW generator set is considered a significant technological achievement, then this power is merely enough to drive a 1.3 million kW large steam turbine generator's water pump. In recent years, the technology for large water pumps has developed rapidly, with the diameter of the impeller of axial flow pumps reaching 7 m, and the diameter of submersible pump impellers reaching 1 m. The power of small double-suction centrifugal pumps used in urban and industrial water supply projects has reached 5560 kW.
      2. Commercialization, high-speed development
      The single-stage lift of boiler water systems has already reached records of 120 m. To further achieve high lift, it is necessary to increase the pump's rotational speed. In the future, with continuous improvements in cavitation, material strength, and other issues, the pump's rotational speed may further trend towards high-speed development. In the pump industry, this trend towards high-speed development is a global phenomenon.
      3. Series production, generalization, standardization
      The series production, generalization, and standardization (referred to as the 'three standardizations') of products are an inevitable requirement of modern industrial production processes. In 1985, the International Organization for Standardization established the essential dimensions and specifications for centrifugal pumps with a rated pressure of 7 bar (ISO 2858:1975). The performance range of this standard pump is: flow rate of 6.3 to 4000 m³/h, lift of 25 to 125 m.
Currently, in Europe, all water pumps that meet this specification are sold as standard pumps. Since 1958, China has also made significant progress in standardizing pump types, series classification, and standardized dimensions. The main components of pumps, such as brackets, suspensions, and bearing housings, have already been standardized, and the degree of 'three standardizations' of products is continuously improving.
       In the future, with the development of atomic energy and chemical industries, there will be further demands for the development of various special pump products with high speed, high temperature and pressure resistance, high efficiency, and large capacity; at the same time, there is a need to continuously improve the quality and level of existing conventional products. All of this means that innovations must be made in a series of aspects, including theoretical foundations, calculation techniques, model testing, measurement methods, material selection, and processing technology. The future is an extension and continuation of the present, and this task is both glorious and arduous.